Oleg's suggestion about MPS didn't work, but it was fun. Instead of dyinginstantly, a USB mouse pauses about 9 times before it finally halts. Thedevice in dmesg also disconnects/reconnects 9 times before it is unable toassign a device number again to the mouse. PS/2 still locks the entiremachine. Loading and unloading usb-uhci.o does reinitialize the USB mousefor a while, so it is fixable w/o rebooting.

This is also interesting. You appear to not have the strange ACPI deviceat hardware interrupt 9 that I do. While the VP6 BIOS does not have theoption to turn off ACPI, perhaps I should try one of the hacked bioses atabitvp6.com to turn off ACPI (maybe it is the culprit..) This is mycurrent situation (right after a USB lock):